Association between 21-gene-assay and detection of disseminated tumor cells in patients with early breast cancer: results from the IRMA trial

PURPOSE

Disseminated tumor cells (DTCs) in the bone marrow (BM) are known to be of prognostic value for patients with early breast cancer (EBC). In addition to histopathological features, multigene expression assays, such as the commercially available 21-gene Breast Recurrence Score® assay, have been validated for evaluating prognosis and making decisions concerning adjuvant treatment in EBC. In a previous retrospective study from our group, the 21-gene assay was shown to be associated with DTC-detection. A secondary endpoint of the prospective IRMA trial was to evaluate the association between Recurrence Score® (RS) result and tumor cell dissemination in patients with EBC.

METHODS

DTC-status and RS result were assessed in patients with ER-positive/HER2-negative EBC with 0-3 pathologic lymph nodes who underwent primary surgical treatment at the Department for Women's Health of Tuebingen University, Germany.

RESULTS

Patients with a high RS result (≥ 26) were more frequently DTC-positive (22.6%) than patients with a low RS result (8.6%, p = 0.034). The odds for DTC-positivity increased with rising RS values (p = 0.047).

CONCLUSION

We therefore confirm that a high genomic risk is associated with tumor cell dissemination into the BM. Further trials are needed to investigate whether therapeutic decisions could be further individualized by combining DTC-status and prognostic gene signature testing.

Recurrence Score® Result Impacts Treatment Decisions in Hormone Receptor-Positive, HER2-Negative Patients with Early Breast Cancer in a Real-World Setting-Results of the IRMA Trial

BACKGROUND

Patients with hormone receptor-positive (HR+), HER2-negative (HER2-) early breast cancer (eBC) with a high risk of relapse often undergo adjuvant chemotherapy. However, only a few patients will gain benefit from chemotherapy. Since classical tumor characteristics (grade, tumor size, lymph node involvement, and Ki67) are of limited value to predict chemotherapy efficacy, multigene expression assays such as the Oncotype DX® test were developed to reduce over- and undertreatment. The IRMA trial analyzed the impact of Recurrence Score® (RS) assessment on adjuvant treatment recommendations.

MATERIALS AND METHODS

The RS result was assessed in patients with HR+/HER2- unilateral eBC with 0-3 pathologic lymph nodes who underwent primary surgical treatment at the Department for Women's Health of Tuebingen University, Germany. Therapy recommendations without knowledge of the RS result were compared to therapy recommendations with awareness of the RS result.

RESULTS

In total, 245 patients underwent RS assessment. Without knowledge of the RS result, 92/245 patients (37.6%) would have been advised to receive chemotherapy. After RS assessment, 56/245 patients (22.9%) were advised to undergo chemotherapy. Chemotherapy was waived in 47/92 patients (51.1%) that were initially recommended to receive it. Chemotherapy was added in 11/153 patients (7.2%) that were recommended to not receive it initially.

SUMMARY

Using the RS result to guide adjuvant treatment decisions in HR+/HER2- breast cancer led to a substantial reduction of chemotherapy. In view of the results achieved in prospective studies, the RS result is among other risk-factors suitable for the individualization of adjuvant systemic therapy.

Improved preoperative risk stratification in endometrial carcinoma patients: external validation of the ENDORISK Bayesian network model in a large population-based case series

PURPOSE

Preoperative risk stratification of newly diagnosed endometrial carcinoma (EC) patients has been hindered by only moderate prediction performance for many years. Recently ENDORISK, a Bayesian network model, showed high predictive performance. It was the aim of this study to validate ENDORISK by applying the model to a population-based case series of EC patients.

METHODS

ENDORISK was applied to a retrospective cohort of women surgically treated for EC from 2003 to 2013. Prediction accuracy for LNM as well as 5-year DSS was investigated. The model's overall performance was quantified by the Brier score, discriminative performance by area under the curve (AUC).

RESULTS

A complete dataset was evaluable from 247 patients. 78.1% cases were endometrioid histotype. The majority of patients (n = 156;63.2%) had stage IA disease. Overall, positive lymph nodes were found in 20 (8.1%) patients. Using ENDORISK predicted probabilities, most (n = 156;63.2%) patients have been assigned to low or very low risk group with a false-negative rate of 0.6%. AUC for LNM prediction was 0.851 [95% confidence interval (CI) 0.761-0.941] with a Brier score of 0.06. For 5-year DSS the AUC was 0.698 (95% CI 0.595-0.800) as Brier score has been calculated 0.09.

CONCLUSIONS

We were able to successfully validate ENDORISK for prediction of LNM and 5-year DSS. Next steps will now have to focus on ENDORISK performance in daily clinical practice. In addition, incorporating TCGA-derived molecular subtypes will be of key importance for future extended use. This study may support further promoting of data-based decision-making tools for personalized treatment of EC.

Electrosurgery and Other Technical Advancements in Minimally Invasive Gynecological Surgery - An Update

Electrosurgery in gynecology has changed over the past few decades. The use of energy-based devices, especially in minimally invasive procedures, is extremely important for preparation, short reconvalescence and patient safety. Recently, there have been major advances in energy-based surgical devices that have further shortened OR time and increased patient safety. Although bipolar and monopolar electrosurgery is still very important, the introduction of high-frequency ultrasound in gynecologic surgery has improved cutting and coagulation by lowering thermal damage in the surrounding tissue. Furthermore, new technical inventions have fundamentally changed the treatment of specific diseases. The introduction of ablation in the therapy of uterine fibroids, for example, has made conventional myomectomy no longer necessary in some cases, as necrosis of fibroids can be induced by placing very small thermal probes into the fibroids. Robotic surgery will change the face of gynecological surgery in the near future, as the initial studies could show lower surgical morbidity and faster recovery of patients after robotic-assisted laparoscopy. In this article we provide a short overview of current technical advances, review possible indications as well as limitations, and take a look into the future of minimally invasive surgery in gynecology.

The Laminin Receptors Basal Cell Adhesion Molecule/Lutheran and Integrin α7β1 on Human Hematopoietic Stem Cells

In the adult organism, hematopoietic stem and progenitor cells (HSPC) reside in the bone marrow (BM) in specialized hematopoietic stem cell niches of which the extracellular matrix (ECM) is an integral component. Laminins (LM) are a family of heterotrimeric ECM molecules of which mainly family members containing an α4 or α5 chain are expressed in cells from BM niches and involved in HSPC homing and proliferation. Various integrin and non-integrin laminin receptors have been identified and characterized. Among these, the integrins α6β1 and α3β1 were reported to be strongly expressed on human and mouse HSPC. In the present study, we focus on two further specific laminin receptors, namely integrin α7β1 and basal cell adhesion molecule/Lutheran (BCAM/Lu). Using RT-PCR analyses, immunofluorescence staining, immunoblotting and flow cytometry, we show that both are strongly expressed by human lineage-negative CD34 + HSPC. Treatment with function-blocking antibodies against BCAM/Lu neither inhibits the strong adhesive interaction of CD34 + HSPC with LM-511/LM-521 nor the LM-511/LM-521 mediated changes in CD34 + HSPC proliferation, but however, influences the cytokine-induced differentiation of HSPC in colony formation assays. In addition, stromal-derived factor (SDF) 1α-mediated transmigration of CD34 + HSPC through an endothelial cell layer was effectively diminished by BCAM/Lu antibodies, suggesting a direct involvement of BCAM/Lu in the migration process. This study indicates that both laminin receptors newly identified on human CD34 + HSPC should be taken into consideration in future studies.

Voluntary Control of Agonist Premotor Silence Preceding Limb Movements of Maximal Effort

The ability to gain voluntary control over agonist premotor silence through electromyographic (EMG) feedback was examined in healthy subjects performing maximal horizontal elbow flexions. Subjects exhibiting premotor silence on at least 50% of the pretest trials showed significantly greater peak angular velocity than subjects who produced the silent period on fewer than 20% of the trials during the pretest. The latter subjects acquired control of agonist premotor silence with practice and graphic feedback regarding their EMG patterns. The subjects who were the most successful in learning to produce the silent period increased their angular velocity to the level of the subjects who naturally exhibited the inhibition. The less successful subjects showed smaller increases in velocity. The data provide further evidence that premotor silence is primarily under central influence, that its control can be acquired, and that it may be functionally related to contractile rate.

An Electronic Patient-Reported Outcome Tool for the FACT-B (Functional Assessment of Cancer Therapy-Breast) Questionnaire for Measuring the Health-Related Quality of Life in Patients With Breast Cancer: Reliability Study

Background

The most frequent malignant disease in women is breast cancer. In the metastatic setting, quality of life is the primary therapeutic goal, and systematic treatment has only a limited effect on survival rates; therefore, the concept of the health-related quality of life (HRQoL) and measurement of patient-reported outcomes (PROs) are gaining more and more importance in the therapy setting of diseases such as breast cancer. One of the frequently used questionnaires for measuring the HRQoL in patients with breast cancer is the Functional Assessment of Cancer Therapy-Breast (FACT-B). Currently, paper-based surveys still predominate, as only a few reliable and validated electronic-based questionnaires are available. ePRO tools for the FACT-B questionnaire with proven reliability are missing so far.

Objective

The aim of this study was to analyze the reliability of tablet-based measurement of FACT-B in the German language in adjuvant (curative) and metastatic breast cancer patients.

Methods

Paper- and tablet-based questionnaires were completed by a total of 106 female adjuvant and metastatic breast cancer patients. All patients were required to complete the electronically based (ePRO) and paper-based version of the FACT-B. A frequency analysis was performed to determine descriptive sociodemographic characteristics. Both dimensions of reliability (parallel forms reliability using Wilcoxon test and test of internal consistency using Spearman ρ) and agreement rates for single items, Kendall tau for each subscale, and total score were analyzed.

Results

High correlations were shown for both dimensions of reliability (parallel forms reliability and internal consistency) in the patients’ response behavior between paper-based and electronically based questionnaires. Regarding the reliability test of parallel forms, no significant differences were found in 35 of 37 single items, while significant correlations in the test for consistency were found in all 37 single items, in all 5 sum individual item subscale scores, as well as in total FACT-B score.

Conclusions

The ePRO version of the FACT-B questionnaire is reliable for patients with breast cancer in both adjuvant and metastatic settings, showing highly significant correlations with the paper-based version in almost all questions all subscales and the total score.

Ultrasound guided core needle biopsy prior to thermo ablative treatment of uterine tumors: first results

PURPOSE

This study aimed at evaluating the diagnostic yield for core needle biopsies of uterine fibroids before laparoscopic radiofrequency volumetric thermal ablation (RFVTA) with the aim of sonographic imaging. This study was in the context of a randomized, prospective, single-center, longitudinal comparative study in which RFVTA and laparoscopic myomectomy for symptomatic uterine fibroids were compared.

METHODS

All patients of the RFVTA-arm received a core needle biopsy under the guidance of an intraoperative laparoscopic ultrasound system. The Tissue samples were observed histologically.

RESULTS

24 patients were included and received in the median 3.17 biopsies (range 2-7). 45.8% of the fibroids were intramural. In 92% uterine leiomyoma was detected, in 4% a cell rich leiomyoma and in 4% a smooth muscle tumor with uncertain malignant potential (STUMP). There were no complications caused by core needle biopsy.

CONCLUSIONS

Ultrasound guided core needle biopsy can be used to receive a histological result before treating uterine fibroids with thermo surgical methods like RFVTA.

Reliability of an e-PRO Tool of EORTC QLQ-C30 for Measurement of Health-Related Quality of Life in Patients With Breast Cancer: Prospective Randomized Trial

BACKGROUND

Breast cancer represents the most common malignant disease in women worldwide. As currently systematic palliative treatment only has a limited effect on survival rates, the concept of health-related quality of life (HRQoL) is gaining more and more importance in the therapy setting of metastatic breast cancer. One of the major patient-reported outcomes (PROs) for measuring HRQoL in patients with breast cancer is provided by the European Organization for Research and Treatment of Cancer (EORTC). Currently, paper-based surveys still predominate, as only a few reliable and validated electronic-based questionnaires are available. Facing the possibilities associated with evolving digitalization in medicine, validation of electronic versions of well-established PRO is essential in order to contribute to comprehensive and holistic oncological care and to ensure high quality in cancer research.

OBJECTIVE

The aim of this study was to analyze the reliability of a tablet-based measuring application for EORTC QLQ-C30 in German language in patients with adjuvant and (curative) metastatic breast cancer.

METHODS

Paper- and tablet-based questionnaires were completed by a total of 106 female patients with adjuvant and metastatic breast cancer recruited as part of the e-PROCOM study. All patients were required to complete the electronic- (e-PRO) and paper-based versions of the HRQoL EORTC QLQ-C30 questionnaire. A frequency analysis was performed to determine descriptive sociodemographic characteristics. Both dimensions of reliability (parallel forms reliability [Wilcoxon test] and test of internal consistency [Spearman rho and agreement rates for single items, Pearson correlation and Kendall tau for each scale]) were analyzed.

RESULTS

High correlations were shown for both dimensions of reliability (parallel forms reliability and internal consistency) in the patient's response behavior between paper- and electronic-based questionnaires. Regarding the test of parallel forms reliability, no significant differences were found in 27 of 30 single items and in 14 of 15 scales, whereas a statistically significant correlation in the test of consistency was found in all 30 single items and all 15 scales.

CONCLUSIONS

The evaluated e-PRO version of the EORTC QLQ-C30 is reliable for patients with both adjuvant and metastatic breast cancer, showing a high correlation in almost all questions (and in many scales). Thus, we conclude that the validated paper-based PRO assessment and the e-PRO tool are equally valid. However, the reliability should also be analyzed in other prospective trials to ensure that usability is reliable in all patient groups.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03132506; https://clinicaltrials.gov/ct2/show/NCT03132506 (Archived by WebCite at http://www.webcitation.org/6tRcgQuou).

PD-1 and PD-L1 Immune Checkpoint Blockade to Treat Breast Cancer

Immune checkpoint inhibition represents a major recent breakthrough in the treatment of malignant diseases including breast cancer. Blocking the programmed death receptor-1 (PD-1) and its ligand, PD-L1, has shown impressive antitumor activity and may lead to durable long-term disease control, especially in the triple-negative subtypes of breast cancer (TNBC). Although immune checkpoint blockade is generally well tolerated, specific immune-related adverse events (irAEs) may occur. This review summarizes the clinical efficacy, perspectives, and future challenges of using PD-1/PD-L1-directed antibodies in the treatment of breast cancer.

Disseminated tumor cells from the bone marrow of patients with nonmetastatic primary breast cancer are predictive of locoregional relapse

BACKGROUND

Disseminated tumor cells (DTCs) are detectable in the bone marrow (BM) of patients with primary breast cancer (PBC) and predictive of an impaired prognosis. This large trial aimed to analyze the impact of DTC detection on locoregional relapse (LR).

PATIENTS AND METHODS

Patients with nonmetastatic PBC were eligible for this analysis. BM aspiration (BMA1) was carried out during primary surgery and DTCs were detected by using immunocytochemistry (A45-B/B3 antibody against pancytokeratin) and morphological criteria. At the time of LR, a subgroup of patients with nonmetastatic and operable LR received a secondary BM aspiration (BMA2).

RESULTS

A total of 3072 patients were included into the analysis. Of these, 732 (24%) presented with DTCs at BMA1. One hundred thirty-nine patients experienced LR and 48 of these (35%) were initially DTC positive. DTC detection was significantly associated with an increased risk of LR in univariate (P = 0.002) and multivariate analysis (P = 0.009) with a hazard ratio of 1.65 (95% confidence interval 1.13-2.40). Of the patients with LR, 55 patients were available for BMA2 and 17 of these (32%) were DTC positive. DTC detection at the time of LR was indicative of impaired overall survival (univariate analysis, P = 0.037).

CONCLUSIONS

DTC detection in patients with PBC is associated with an increased risk of LR, indicating that tumor cells may have the ability to recirculate from the BM to the site of the primary tumor. The impaired prognosis associated with DTC detection at the time of LR may help to identify patients that are in need for additional or more aggressive treatment.

Detection and prevalence of disseminated tumor cells from the bone marrow of early stage male breast cancer patients

Male breast cancer (mBC) is a rare entity. As detection of disseminated tumor cells (DTCs) in the bone marrow of females with early stage breast cancer is a promising prognostic marker, we aimed to determine the prevalence and prognostic value of DTCs in mBC. Bone marrow aspirates were collected from male patients undergoing primary surgery for early stage breast cancer (T1-4, N0-2, M0) at Tuebingen University, Germany, between January 2001 and April 2015. DTCs were identified by immunocytochemistry (pancytokeratin antibody A45/B-B3) and cytomorphology. 24 patients with mBC were included into the analysis. DTCs were detected in four of these (17 %). There was no significant association between the DTC status and any other clinicopathological parameter. Also, no significant impact of the DTC status on DFS or OS could be observed. DTCs are detectable in patients with early stage mBC. The detection rate is comparable to that in women. No associations between DTCs and clinicopathological features or prognosis were observed, which is most likely due to the small sample size. The detection of DTCs in male patients with early stage breast cancer emphasizes the transmission of future clinical applications for DTCs from women to men.

Placing the Perceptual-Cognitive Approach in Perspective

Although some features of the "psychological approach" are compelling, its immediate impact as a theoretical framework appears to be limited by somewhat ambiguous key constructs and the lack of appropriate placement vis-a-vis extant conceptual views.

An examination of rapid positioning movements with spatiotemporal constraints

Unidirectional positioning movements with spatiotemporal constraints were examined as a test of impulse-timing theory (Schmidt, 1976; 1980; Wallace, 1981). Movements were examined at the kinematic, kinetic, and neuromuscular levels in three experiments. In the first experiment, displacement was held constant while five different movement times were examined. Both amplitudes and durations of the EMG and the kinetic variables were related to movement time. The results generally support the impulse-timing model. In the second experiment, movements were performed to a target at each of four distances in a constant movement time. EMG and force amplitudes and, unexpectedly, accelerative-force duration were modulated to achieve changes in displacement when movement time was constant. In the third experiment, movement time and displacement were simultaneously varied resulting in four conditions with equal average velocities. The results of this experiment were not as clear and exhibited individual differences. EMG duration did not always vary with changes in movement time. The results of all three experiments could not be adequately accounted for by the impulse-timing model.

Dissociating the structural and metrical specifications of bimanual movement

Synchronization strength was investigated during the bimanual performance of movements with fundamentally different spatiotemporal features. A flexion (unidirectional) movement was made by the nondominant limb together with a flexion-extension-flexion (reversal) movement by the dominant limb. In contrast with previous studies on bimanual coordination, the movements differed from each other with respect to qualitative (structural) as well as quantitative (metrical) characteristics. Accordingly, the main task goal was to dissociate the limbs' actions at both these levels. Findings of Experiment 1 (within-subject) and Experiment 2 (between-subject) revealed a mutual synchronization effect that was evident at various levels of movement description and that was essentially asymmetric in nature: The unidirectional movement was more attracted to the reversal movement than vice versa. The intrusive nature of synchronization prevented full metrical and structural dissociation of the upper-limbs' actions, although individual differences were apparent and reflected fundamentally different coordination modes.

Bilateral facilitation of motor control in chronic hemiplegia

The present study addressed the efficacy of concurrently moving both arms, with and without a load added to the uninvolved arm, in facilitating the quality of movement of the involved side in individuals with moderate, chronic hemiplegia. Six hemiplegic cerebrovascular accident (CVA) subjects with left-hemisphere lesions participated in the study. The four males and two females ranged from 46 to 77 years of age and 30-96 months post-CVA. All subjects scored at least 70% on the Fugl-Meyer test of motor function. The task was to perform discrete unilateral and bilateral elbow extensions in the horizontal plane. The movements were 45 degrees in amplitude and were to terminate in a 10 degrees target zone that was indicated by an illustration of a coffee mug. The instructions were to move toward the mug as smoothly as possible in a movement time (MT) determined to be 20% longer than their minimal MT for that distance. The primary dependent variable was the percentage of continuous vs. discontinuous trajectories observed in each condition, based on whether or not a transient hesitation or reversal was observed. Phase of peak velocity was also quantified as a general indication of the symmetry of the velocity profile. Three of the six subjects exhibited a greater percentage of continuous movements of the involved arm in the nonloaded bilateral condition than the unimanual condition. Five subjects benefited when the uninvolved arm was inertially loaded in the bilateral condition when compared with unimanual performance. Only the oldest subject failed to exhibit facilitation. Peak velocity phase tended to normalize toward symmetry in the bilateral conditions. These findings are consistent with prior evidence that the control of the involved arm improves during bimanual performance for some hemiplegic subjects. It further suggests loading the uninvolved arm may benefit some subjects with respect to unimanual performance, with age perhaps playing a role in determining efficacy.

Generation of bimanual trajectories of disparate eccentricity: levels of interference and spontaneous changes over practice

The authors examined intermanual interactions of 2 hands that were required to concurrently follow trajectories that differed in eccentricity. Ten healthy participants attempted to learn to trace 2 figures, a circle and an ellipse, with bilaterally isochronous (1:1) timing demands. Initial unimanual trials were followed by bilateral practice comprising 750 movement cycles. Two objectives were addressed: The authors' primary aim was to determine if kinematic interlimb interference is evident independent of spatial and temporal interference and to observe the potential practice-related changes in the nature of that interference. That test was afforded by participants' natural tendency to draw a circle with a relatively constant tangential velocity and an ellipse with a systematically varying velocity. A second aim was to observe the nature of spontaneous changes in the performance of each individual effector, and in the relationship between effectors, across practice. Those objectives were specifically addressed in a context in which augmented feedback was not available to direct the learners' attention to a particular feature of performance. The results suggested that interlimb assimilation of spatial features is the primary source of interference for that task and that apparent effects at the kinematic level are the secondary, indirect product of spatial coupling. Those results were found across blocks of practice. With respect to nondirected performance changes, substantially less improvement was evident in the performance of each individual effector than in the reduction of interlimb interference. Specifically, no practice-related changes in temporal variability or velocity bias, and minimal changes in trajectory smoothness, were evident in individual limbs. Conversely, significant reductions were observed in the variability of relative phase between limbs and in the magnitude of interlimb phase lag.

Hierarchical control of different elbow-wrist coordination patterns

The present paper focused on the role of mechanical factors arising from the multijoint structure of the musculoskeletal system and their use in the control of different patterns of cyclical elbow-wrist movements. Across five levels of cycling frequency (from 0.45 Hz up to 3.05 Hz), three movement patterns were analyzed: (1) unidirectional, including rotations at the elbow and wrist in the same direction; (2) bidirectional, with rotation at the joints in opposite directions, and (3) free-wrist pattern, which is characterized by alternating flexions and extensions at the elbow with the wrist relaxed. Angular position of both joints and electromyographic activity of biceps, triceps, the wrist flexor, and the wrist extensor were recorded. It was demonstrated that control at the elbow was principally different from control at the wrist. Elbow control in all three patterns was similar to that typically observed during single-joint movements: elbow accelerations-decelerations resulted from alternating activity of the elbow flexor and extensor and were largely independent of wrist motion at all frequency plateaus. The elbow muscles were responsible not only for the elbow movement, but also for the generation of interactive torques that played an important role in wrist control. There were two types of interactive torques exerted at the wrist: inertial torque arising from elbow motion and restraining torque arising from physical limits imposed on wrist rotation. These interactive torques were the primary source of wrist motion, whereas the main function of wrist-muscle activity was to intervene with the interactive effects and to adjust the wrist movement to comply with the required coordination pattern. The unidirectional pattern was more in agreement with interactive effects than the bidirectional pattern, thus causing their differential difficulty at moderate cycle frequencies. When cycling frequency was further increased, both the unidirectional and bidirectional movements lost their individual features and acquired features of the free-wrist pattern. The deterioration of the controlled patterns at high cycling frequencies suggests a crucial role for proprioceptive information in wrist control. These results are supportive of a hierarchical organization of control with respect to elbow-wrist coordination, during which the functions of control at the elbow and wrist are principally different: the elbow muscles generate movement of the whole linkage and the wrist muscles produce corrections of the movement necessary to fulfill the task.

Coping with systematic bias during bilateral movement

The present studies examined the nature of kinematic interlimb interference during bilateral elbow movements of 1:1, 2:1 and 3:1 frequency ratios and the manner in which subjects cope with coordination bias. Analysis of movement trajectories in the first experiment indicated progressively greater angular velocity assimilation across 2:1 and 3:1 conditions. The desired temporal relationship was maintained by slowing or pausing the low-frequency movement at peak extension while the high-frequency arm produced intervening cycles. An increase in amplitude was also evident for concurrent, homologous cycles. Movement smoothness was emphasized and additional practice was provided in a second experiment. This resulted in dissociated peak angular velocity between limbs and eliminated hesitations and amplitude effects. Bias was still evident, however, as an intermittent approach toward a 1:1 ratio within each cycle. This systematic tendency was somewhat greater at the lower of two absolute frequency combinations but was not influenced by the role of each arm in producing the higher or lower frequency movement. The findings from the first experiment suggest that subjects initially accommodate interlimb kinematic assimilation, while producing the intended timing ratio, by intermittently slowing or pausing the lower-frequency movement. This attenuates the need for bilaterally-disparate movement parameters and provides additional time for organizing residual kinematic differences, perhaps reducing "transient coupling." Evidence from the second experiment indicates that subtle relative motion preferences are still evident following sufficient practice to perform the movements smoothly. The within-cycle locations of the points of greatest interlimb bias for the 2:1 rhythms were positively displaced from those previously observed for 1:1 oscillations. The persistent coordination tendencies noted in both experiments perhaps reflect an assimilation/compensation cycle and constitute one potential source of the systematic error that often emerges during the acquisition of complex skills.

Exploring interlimb constraints during bimanual graphic performance: effects of muscle grouping and direction

Past studies on bimanual coordination have revealed a general preference to move the limbs in a symmetrical fashion, also denoted as the in-phase mode. Its counterpart, the asymmetrical or anti-phase mode, is performed with lower degrees of accuracy and stability. This ubiquitous tendency to activate the homologous muscle groups is referred to as the muscle grouping constraint (egocentric constraint). The present study confirmed the generalizability of this constraint across various coordination patterns, performed in the horizontal plane. In addition, evidence was generated that movement direction in extrinsic space also constrains bimanual coordination (allocentric constraint). Overall, the present observations suggest that direction is an important movement parameter that is encoded in the central nervous system and that is subject to interactions between the neural specifications of both limbs.

The organization of patterns of multilimb coordination as revealed through reaction time measures

Simple visual reaction time (RT) during the performance of sagittal movements of the upper and/or lower limbs was investigated. Experiment 1 demonstrated that RTs increased when more limbs were to be moved simultaneously. This effect was more apparent for the upper than for the lower limbs. Experiment 2 allowed a separation of RT into premotor time (PMT) and motor time (MOT) components through analysis of electromyographic activity, and showed that these longer response delays were associated with increased PMTs. This suggests that the time required for the central organization of movements increased as more limbs were to be controlled simultaneously. Compared to single-limb performance conditions, the increases in RT were much larger in the upper limbs (up to 16%) than in the lower limbs (up to 5%) when limb segments were added. During single-limb conditions, RTs in the upper limbs tended to be smaller than in the lower limbs, in accordance with efferent nerve conduction time estimates. Conversely, the lower limb(s) was (were) initiated before the upper limb(s) when both effector types were moved simultaneously. This pattern of activation is reminiscent of the organization of postural control during upright standing, where goal-directed arm activity is preceded by (bilateral) leg activity to anticipate for the upcoming postural destabilization. Finally, hemifield manipulations in experiment 2 revealed faster RTs and PMTs for stimuli presented in the right visual field in comparison with the left field. This advantage was evident for ipsilateral as well as contralateral responses and supports the pre-eminence of the left hemisphere in the complex organization of gross motor responses.

Acquiring bimanual skills: contrasting forms of information feedback for interlimb decoupling

The present experiments addressed the learner's capability to perform different upper-limb actions simultaneously with the help of various sources of information feedback. An elbow flexion movement was made in the left limb together with a flexion-extension-flexion movement in the right limb. Interlimb interactions were assessed at the structural as well as the metrical level of movement specification during acquisition and retention. Despite a strong initial tendency for the limbs to be synchronized, findings revealed that Ss became gradually more successful in interlimb decoupling as a result of practice with augmented feedback. However, detailed knowledge of movement kinematics was no more effective than global outcome information for interlimb decoupling, indicating that knowledge of results may have more potential for acquiring multiple degree-of-freedom tasks than previously believed. Finally, the data support the general notion that learning new coordination tasks involves the suppression of preexisting preferred coordination tendencies, which is often a prerequisite for building new coordination modes.

Acquiring bimanual skills: contrasting forms of information feedback for interlimb decoupling

The present experiments addressed the learner's capability to perform different upper-limb actions simultaneously with the help of various sources of information feedback. An elbow flexion movement was made in the left limb together with a flexion-extension-flexion movement in the right limb. Interlimb interactions were assessed at the structural as well as the metrical level of movement specification during acquisition and retention. Despite a strong initial tendency for the limbs to be synchronized, findings revealed that Ss became gradually more successful in interlimb decoupling as a result of practice with augmented feedback. However, detailed knowledge of movement kinematics was no more effective than global outcome information for interlimb decoupling, indicating that knowledge of results may have more potential for acquiring multiple degree-of-freedom tasks than previously believed. Finally, the data support the general notion that learning new coordination tasks involves the suppression of preexisting preferred coordination tendencies, which is often a prerequisite for building new coordination modes.

Potentiating ballistic limb movements through voluntary production of the stretch-shorten cycle

The purpose of this study was to examine the effect of learning to produce voluntarily a basic biomechanical mechanism, the stretch-shorten cycle (SSC), on the acceleration of a ballistic arm movement. The task required an elbow flexion at maximal effort performed with the forearm resting upon a horizontal manipulandum. Subjects in three groups received either no augmented feedback, feedback concerning the velocity of the flexion, or a combination of feedback on velocity and feedback related to the rate of stretch of the SSC during 80 training trials. The training trials were preceded by a pretest and followed by a posttest without feedback. Analyses showed that the subjects receiving feedback concerning the SSC exhibited earlier and greater peak angular acceleration than the other groups. These findings provide evidence that acquiring the control of relevant, basic mechanisms like the SSC may be useful in facilitating tasks requiring limb movements of maximal effort.

Adaptive Tuning of Interlimb Attraction to Facilitate Bimanual Decoupling

Motor skills that require limbs to concurrently produce different spatiotemporal patterns are often quite difficult to learn. This article outlines a general strategy for training subjects to perform skills that require such disparate limb movements. The strategy is based on the notion that certain preferred movement patterns naturally emerge through the dynamics of the perceptual-motor system, even when quite different movements are intended. The training strategy proposes that the acquisition of relative motion patterns that diverge from preferred patterns can be facilitated by initially "tuning" system dynamics to reduce interlimb attraction. The schedule for the dynamical tuning is adopted from the adaptive training method previously applied to tracking tasks. Preliminary evidence is provided in support of this strategy for learning a bimanual task requiring both structural and metrical interlimb decoupling.

Uniqueness of interval and continuous training at the same maintained exercise intensity

The present study sought to evaluate the inconsistencies previously observed regarding the predominance of continuous or interval training for improving fitness. The experimental design initially equated and subsequently maintained the same relative exercise intensity by both groups throughout the program. Twelve subjects were equally divided into continuous (CT, exercise at 50% maximal work) or interval (IT, 30 s work, 30 s rest at 100% maximal work) training groups that cycled 30 min day-1, 3 days.week-1, for 8 weeks. Following training, aerobic power (VO2max), exercising work rates, and peak power output were all higher (9-16%) after IT than after CT (5-7%). Vastus lateralis muscle citrate synthase activity increased 25% after CT but not after IT. A consistent increase in adenylate kinase activity (25%) was observed only after IT. During continuous cycling testing the CT group had reduced blood lactate (lab) levels and respiratory quotient at both the same absolute and relative (70% VO2max) work rates after training, while the IT group displayed similar changes only at the same absolute work rates. By contrast, both groups responded similarly during intermittent cycling testing with lower lab concentrations seen only at absolute work rates. These results show that, of the two types of training programs currently employed, IT produces higher increases in VO2max and in maximal exercise capacity. Nevertheless, CT is more effective at increasing muscle oxidative capacity and delaying the accumulation of lab during continuous exercise.

Control of asymmetrical bimanual movements

When movements are performed together in the upper-limbs, a strong tendency emerges to synchronize the patterns of motor output. This is most apparent when trying to do different things at the same time. The present experiment explored the simultaneous organization and control of spatiotemporally different movements. There were two practice conditions: symmetrical and asymmetrical. In the symmetrical condition, subjects performed a series of unidirectional elbow flexion movements, followed by a series of elbow flexion-extension-flexion (reversal) movements in both limbs simultaneously. In the asymmetrical practice condition, subjects performed the unidirectional movement in the left limb together with the reversal movement in the right limb. Findings revealed a tendency for each limb movement to assimilate the features of its counterpart under the latter condition. This effect was "asymmetrical" in that the unidirectional movement was more attracted to the reversal movement than vice versa. Nevertheless, subjects were able to partly suppress this synchronization tendency as was evident from the moderate cross correlations between the angular acceleration patterns of both limb movements and from an increasingly successful differentiation of the activity levels in the right and left limb muscles. All together, these findings provide evidence for some degree of parallel control of spatiotemporally different actions. The data are discussed in view of the possible suppression of a bilaterally distributed motor control system, that is mainly held responsible for activiting proximal limb musculature.

Kinetic Attraction During Bimanual Coordination

Two experiments examined the effects of independent variations in kinetic and kinematic requirements on interlimb coupling during a bimanual task. The goal of the investigation was to provide preliminary evidence regarding one general class of physical variables that constrains discrete bimanual movements. Subjects attempted to execute a smooth unidirectional movement with the left arm, along with a three-segment reversal movement with the right arm. The first experiment manipulated the torque required to produce the reversal action, while movement duration and average angular velocity were held constant for both limbs. Several indications of increased interlimb coupling, due to the kinetic variation, were evident. The converse manipulation was used in the second experiment, with movement time and kinematics (velocity, acceleration) changed independently of joint torque requirements for the reversal limb. No clear effect of kinematics on coupling strength was noted. The results suggest that one variable influencing interlimb attraction toward common spatiotemporal trajectories may be kinetic in nature.

Asymmetric interlimb interference during the performance of a dynamic bimanual task

The control of a dynamic bimanual task was examined by manipulating two independent factors that potentially influence interlimb interference. Subjects attempted to perform a unidirectional movement with either their preferred or nonpreferred arm while concurrently producing a sequential movement with the contralateral arm. The magnitude of force required to produce the more complex, sequential action was manipulated in addition to the arm with which it was performed. The degree of interlimb interference was determined through an analysis of limb kinematics. A clear performance asymmetry was noted, with greater interference evident when the sequential action was generated by the nonpreferred left arm than by the preferred right arm. The level of force needed to produce the sequential movement also directly influenced interlimb interference, but this effect was bilaterally symmetrical. The findings are generally consistent with a hierarchical view of movement organization comprising lateralized hemispheric specialization for the organization of time-domain characteristics of sequential actions, followed by nonlateralized metrical scaling of force parameters. Implications of the findings for "dynamical" descriptions of bimanual actions are also discussed.

Voluntary control of agonist premotor silence preceding limb movements of maximal effort

The ability to gain voluntary control over agonist premotor silence through electromyographic (EMG) feedback was examined in healthy subjects performing maximal horizontal elbow flexions. Subjects exhibiting premotor silence on at least 50% of the pretest trials showed significantly greater peak angular velocity than subjects who produced the silent period on fewer than 20% of the trials during the pretest. The latter subjects acquired control of agonist premotor silence with practice and graphic feedback regarding their EMG patterns. The subjects who were the most successful in learning to produce the silent period increased their angular velocity to the level of the subjects who naturally exhibited the inhibition. The less successful subjects showed smaller increases in velocity. The data provide further evidence that premotor silence is primarily under central influence, that its control can be acquired, and that it may be functionally related to contractile rate.

The coordination of limb movements with different kinematic patterns

The principles underlying the coordination of limb movements with different spatiotemporal features were explored. After an initial training session in which the same unidirectional movement had to be performed with both upper limbs, subjects attempted to coordinate two different movements in a second session, i.e., the learned unidirectional movement in the left limb and a new double reversal movement in the right limb. The findings uncovered a wide variety in patterns of interlimb dependence among and within subjects, going from a high degree of dependence to relative independence. The relationship between limbs was studied by means of a detailed analysis of the displacement and acceleration patterns and the electromyographic activity of the major muscles involved. The general underlying principle that appeared to account for the diversity in movement organization was this: higher independence between limb movements is achieved when subjects initiate the movements to be coordinated successively. This asynchrony in movement onset can possibly be viewed as an attempt to safeguard against interference.

The Force/Force-Variability Relationship Under Controlled Temporal Conditions

Previously, an inverted U relationship between force and force variability was demonstrated in both static and dynamic responses. Recent research suggests that the inverted U function may be due to a lack of control of the temporal aspects of the response. To investigate this hypothesis, we examined the relationship between force and force variability in rapid movements under controlled temporal conditions. Subjects (N = 4) made rapid reversal responses with a horizontal lever (using elbow flexion and extension) such that the time to reversal (160 ms) and the distance to reversal (45 degrees ) were held constant in each of six load conditions (either 0,.260,.780, 1.040, or 1.560 kg added to the lever). When time to reversal and time to peak acceleration were held constant, a curvilinear relationship between force and force variability resulted, suggesting that the inverted U function is related to control of the temporal aspects of the response.

The influence of agonist premotor silence and the stretch-shortening cycle on contractile rate in active skeletal muscle

Agonist premotor silence (PMS), a brief period of relative quiescence in active skeletal muscle prior to phasic activation, was investigated in subjects performing maximal contractions. The frequency of occurrence and potential function of the silent period were examined for elbow flexions and extensions. PMS was evident for movements in both directions, indicating that the mechanism is not primarily limited to extensors as previously hypothesized. Flexions demonstrating PMS exhibited increased velocity and acceleration; however, kinematic facilitation was only evident on trials exhibiting the muscular stretch-shortening cycle (SSC). The SSC was present on trials lacking PMS, demonstrating that biceps and triceps silence are not the sole determinants of preparatory agonist lengthening for elbow flexions and extensions, respectively. Taken together, the data indicate that agonist PMS is a mechanism under apparent central control that acts concomitantly with mechanical factors to potentiate elbow flexor contractions.

Rapid movements with reversals in direction. II. Control of movement amplitude and inertial load

Transformations of the underlying movement control of rapid sequential (reversal) responses were examined as the movement amplitude (Experiment 1) and moment of inertia (Experiment 2) were altered, with constant movement time. Increases in amplitude and inertia were both met by sharply increased joint torques with a constant temporal structure, suggesting that the alterations may have been governed by a single gain parameter. The durations of various EMG bursts were essentially constant across changes in inertia, supporting a model in which the output of a fixed temporal representation is amplified to alter joint torques. The EMG amplitudes increased greatly with both amplitude and load. However, the fact that the EMG durations increased systematically with increases in distance provided difficulties for this model of amplitude control. The data suggest an economy in motor control in simple agravitational movements, whereby relatively simple transformations of an underlying representation can accommodate large changes in movement amplitude and moment of inertia.

Rapid movements with reversals in direction. I. The control of movement time

Modifications to the underlying motor control of rapid reversal movements (flexion-extension of the elbow) to accommodate experimentally induced changes in the movement time (MT) with constant movement amplitude were examined in man. MT was altered between conditions via instructions and feedback, resulting in seven distinct MT levels (from 100 to 250 ms to the reversal point) with essentially constant movement amplitude. As MT was decreased, the large increases in acceleration were met by two changes in motor control: (a) two- to three-fold increases in the peak accelerations and peak amplitudes of the agonist and antagonist EMGs, and (b) a systematic "compression" of the temporal structure of the entire acceleration-time and EMG-time patterns. This temporal "compression" with increased velocity caused by shifts in MT (distance constant) are considerably different from the constant-duration EMG bursts found when velocity is altered by changing movement distance (where MT is nearly constant). Our findings indicate that MT is a determiner of the temporal structure of rapid actions, and suggest that MT should be regarded as an important controlled variable, and not simply as an emergent property of variations in velocity.

Electrophoresis in the study of diets and digestive rates of seabirds

Attempts were made to identify unknown gut contents of seabirds by protein analysis using electrophoresis. Standards of undigested fish and squid muscle tissue were compared with muscle tissue at various stages of digestion. Digested mixtures of squid (Loligo reynaudi), Pelagic Goby (Sufflogobius bibarbatus) and Cape Anchovy (Engraulis capensis) did not resemble the undigested standards of each species respectively. Electrophoresis could prove useful in the study of differential digestion rates of seabird prey species.

Independent control of initial kinematics and terminal oscillations of rapid positioning movements

Human subjects performed rapid elbow flexions to visual targets. Subjects were instructed to modulate characteristics of the endpoint oscillations while attempting to hold constant the amplitude and duration of the movement itself. Independent control of the initial kinematics and the frequency of terminal oscillations was observed. The view that positioning movements may be subserved by either a two-stage or time-series control system is supported.